The basic purpose of the invention is to provide a mandrel of the above-described type, which assures a simple and deformation-free or at least a minimum deformation clamping of the tool, in particular a hob, in the tool machine. The draw-in spindle which is otherwise often used for this purpose and which extends axially through the mandrel is to be purposefully avoided. The purpose of the deformation-free or minimum deformation clamping assures that operation is performed with a tightening torque which is as small as possible on the nut and yet at a clamping force which is high in spite of it.